A teenager in East Kilbride, Scotland, is on trial for allegedly killing a schoolmate who was blackmailing him.

Craig Roy, 19, admits to repeatedly stabbing Jack Frew, 16, on a bicycle path in a wooded area but denies that he murdered him.

The BBC reports that Roy told police he had performed oral sex on Frew several months before the 2010 murder and that Frew had threatened to tell Roy’s boyfriend about the encounter.

While Roy’s sister told police that her brother had admitted to slitting Frew’s throat, Roy himself told police that he had only taken the knife with him to scare Frew and that everything happened “very, very fast.”